Abstract
Amyloidosis is a multisystem disease which may cause organloss. Renal involvement is the most common clinical problem in amyloidosis,however involvement of endocrin organs is possible. In this study to assessadrenocortical function and to evaluate the usefulness of low dose ACTH testin patients with renal amyloidosis, we determined cortisol, 17-hydroxyprogesteron(17-OHP) and 11-deoxycortisol (11-DOC) responses to both 1 μg and 250 μgSynacthen. We also determined the size of adrenal glands radiologically byusing computerized tomography. Twenty one patients with renal amyloidosisand 16 healthy subjects for hormonal evaluation, and 20 patients with renalamyloidosis and 22 healthy subjects for radiologic evaluation were includedin the study. In four patients (19%) peak serum cortisol levels followingstimulation with the low dose of Synacthen were less than 20 μg/dL (550nmol/L). Two of them had also subnormal cortisol response to the 250 μgSynacthen stimulation test. Basal and stimulated levels of 11-DOC were lowerthan those of control values (p = 0.000and p < 0.01 respectively). The mean11-DOC responses to stimulation with 1 μg Synacthen were also significantlylower than the values obtained after the simulation with 250 μg Synacthen(p < 0.01 and p= 0.000). Cortisol responses to the stimulation with 250 μg Synacthen werealso lower than the control responses (p< 0.05). 17-OHP responses were similar to the control values in both tests.In the radiological evaluation the mean maximum width of right adrenal glandsand the mean anterior and maximum width of left adrenal glands were significantlygreater in the patient group (p < 0.01).In conclusion, adrenal involvement and adrenal insufficiency is common inamyloidosis. Low 11-DOC levels in amyloidosis is a new finding and furtherdetailed studies is required to explain its cause.
INTRODUCTION
Amyloidosis is a multisystem disease which represents a diverse familyof chronic infiltrative disorders characterized by the presence of extracellulardeposit of insoluble fibrillar proteins. There are several varieties of amyloidosis,each of which is identified by the immunochemical nature of the amyloid proteinfibrils Citation[[1]]. The amyloid deposits infiltrateand destroys normal tissues and may cause organ loss. Renal involvement isthe most common clinical problem in amyloidosis, with more than one thirdof patients affected at presentation, typically with proteinuria, nephroticsyndrome and renal failure Citation[[2]]. Involvementof all other organs including endocrine organs is possible Citation[[3]].Several autopsy studies have shown that the involvement rate of adrenal glandswas 47–96%, however clinically significant adrenal insufficiency israre Citation[[2]], Citation[4-5].
To assess adrenocortical function, a rapid ACTH test has been used asa standard procedure when adrenal insufficiency is suspected. In the standardACTH test, 250 μg ACTH-(1–24) is injected intramuscularly or intravenouslyas a bolus and the response of plasma cortisol is evaluated. However, pharmacologicalACTH tests provide information only about the ability of the adrenals to respondto unusual stimuli and may not reflect the daily cortisol secretion or theresponse to minor stresses. Studies in healthy volunteers demonstrated thatlow doses (0.5–1 μg/1.73 m2) of ACTH-(1–24) are sufficientto stimulate the release of cortisol from the adrenal gland Citation[6-7]. ACTH also stimulates the secretion of adrenalandrogens. The responses of these steroids have also been estimated in therapid ACTH test with a standard dose Citation[[6]].
On the other hand, amyloidosis may produce gross enlargement of adrenalglands with simultaneous loss of functioning adrenal cortical tissue Citation[[8]]. However, we could not find any data demonstratingadrenal enlargement in amyloidosis by radiological evaluation.
In this study involvement of the adrenal cortex in patients with renalamyloidosis was assessed by basal cortisol, 17-hydroxyprogesteron (17-OHP),11-deoxycortisol (11-DOC) responses to both 1 μg and 250 μg Synacthen.The results are compared with those of a control group.
PATIENTS AND METHODS
Renal and/or rectal biopsy-proven 21 patients with renal amyloidosis,ranging in age from 12 to 63 (mean 32.68 ± 15.29) years (11 males,10 females) were included in the study. Of 21 patients, two had non nephroticproteinuria, ten patients had nephrotic syndrome (NS), and nine patients hadchronic renal failure (CRF). Two patients with CRF were on continuous ambulatoryperitoneal dialysis, one of them was on hemodialysis program. The controlgroup used for hormonal evaluation was comprised of 10 women, 6 men, agedfrom 21 to 52 (mean 39.94 ± 9.79) years. None of the subjects in thisgroup had clinical or biochemical evidence of hepatic, renal and endocrinedisorders. The control group used for radiological evaluation was comprisedof 12 women, 10 men, aged from 10 to 52 (mean 31.50 ± 10.90) yearsthat the CT scanning with another reason was carried out. All patients andhealthy subjects had given informed consent.
Hormonal Evaluation
ACTH stimulation tests were performed at 15 days interval as 1 μglow dose and 250 μg standard dose using Synacthen (Ciba Geigy Ltd, Germany).Samples of blood were collected between 0800 and0830 am from all patients and healthy subjectsto determine basal plasma cortisol, 17-OHP and 11-DOC levels. Thirty, 60,90 and 120 minutes after the intravenous (iv) administration of 1 μg or250 μg Synacthen further blood specimens were taken. A plasma cortisolvalue of 20.0 μg/dL (550 mmol/L) or more at any time during the test, includingbefore injection, was taken as indicative of normal adrenal function Citation[[9]].
Plasma cortisol, 17-OHP and 11-DOC concentrations were determined byradioimmunoassay using a commercially available kit (ICN Biomedicals, HylandAvenue, Costa Mesa). Intra and inter-assay coefficients of variations were5.1% and 6% for cortisol, 7.8% and 9.8% for 17-OHP, and 2.1% and 11.6% for11-DOC, respectively.
Radiological Evaluation
CT scanning of the adrenals was carried out in 20 patients with amyloidosisand 22 healthy subjects. All CT examinations were done with a third generationscanner (Toshiba 600XT), using 2 mm sections. CT examinations were performedby the same investigator. Measurements of the adrenals were performed at standardabdominal settings. The measurements recorded were: 1. Maximum width of thegland: defined as the maximum width perpendicular to the long axis of thebody of the gland, at the junction of the adrenal limbs and the body. 2. Widthof the adrenal limbs: defined as the maximum width (thickness) of the medialand lateral limbs of the gland perpendicular to the long axis of the limb,and 3. Anterior width of the gland: defined as maximum width cross the longaxis of the anterior limb of the gland when the adrenal gland showed Y configurationCitation[[10]].
The study was approved by the Ethical Committee of the Medical School.
Students' paired and unpaired t-test were used for testing thesignificance of the differences. Data are expressed as means ±SD. p values less than 0.05 were considered statisticallysignificant.
RESULTS
Basal Values
Basal plasma cortisol and 17-OHP concentrations in the patients withrenal amyloidosis were similar to the values in healthy subjects, whereasbasal plasma 11-DOC levels were lower in the patient group than the valuesobtained in control group (p = 0.000) ().
Table 1. Plasma Cortisol, 11-DOC, and 17-OHP Responses to 1 μg and250 μg Synacthen Stimulation Tests
Synacthen Stimulation Test
There were no significant differences in cortisol and 17-OHP responsesto 1 μg Synacthen stimulation test between patient and control groups.While 17-OHP response to 250 μg Synacthen in the patient group was similarto the response in the control group, cortisol responses at 30, 60 and 90minutes were lower in the patient group (p< 0.05). On the other hand, 11-DOC responses to 1 and 250 μg Synacthenin the patient group were lower than the control group(p= 0.000 and p < 0.01 respectively).
The mean cortisol and 17-OHP responses at 90 and 120 minutes to thestimulation with 1 μg Synacthen in both groups were significantly lowerthan the values after the stimulation with 250 μg Synacthen (p < 0.01 and p< 0.001 for cortisol, and p < 0.01and p < 0.05 for 17-OHP). The mean 11-DOCresponses at 30, 60, 90 and 120 minutes to stimulation with 1 μg Synacthenwere significantly lower than the values after stimulation with 250 μgSynacthen in the patient group (p <0.01, p = 0.000). In the control groupthe mean 11-DOC concentration at 120 minute was significantly lower than thevalue obtained after stimulation with 250 μg Synacthen (p< 0.05).
In four (19%) of 21 patients peak serum cortisol levels following stimulationwith the low dose of Synacthen were less than 20 μg/dL (550 nmol/L). Twoof them had also subnormal cortisol responses the 250 μg Synacthen stimulationtest. Cortisol responses to Synacthen stimulation tests in patients and healthysubjects are given in and , respectively.
Table 2. Cortisol Response to Synacthen Stimulation Test in Patientswith Renal Amy-loidosis
Table 3. Cortisol Response to Synacthen Stimulation Test in NormalIndividuals
We also compared the cortisol responses between the patients with CRFand the patients with proteinuria or NS. Basal and 30, 60, 90thminutes cortisol levels in both groups and both doses were similar. Only cortisolresponse at 120 minute to stimulation with 1 μg Synacthen was significantlyhigher in patients with CRF than the patients with proteinuria or NS ().
Table 4. Plasma Cortisol Responses to 1 μg and 250 μg SynacthenStimulation Tests in Patients with CRF and Proteinuria or NS
Radiological Findings
The mean measurements for the right and left adrenal glands of patientsand healthy subjects are shown in . Bothadrenal glands were identified in all patients but not all measurements couldbe made in each patient because of the variable configuration of the adrenalglands. The mean maximum width of right adrenal glands and the mean anteriorwidth and the mean maximum width of left adrenal glands were significantlygreater in the patient group than in the control group (p< 0.05) (). The shows the measurement of adrenal gland in a patient's CT imagination.
Figure 1. Imagination of a patient's adrenal gland on CT.
Table 5. Computerized Tomography Findings of Patients with Renal Amyloidosisand Healthy Subjects
DISCUSSION
The number of reports of endocrine dysfunction in systemic amyloidosisis small. However several autopsy studies have shown moderate to extensivedissemination of amyloid in endocrine organs. The adrenal and thyroid glandsare mainly involved endocrine organs Citation[[2]], Citation[[5]], Citation[11-12].
In amyloidosis, although decreased adrenal reserve has been commonlyreported, clinically significant adrenal insufficiency is rare Citation[[4]]. However death from Addisonian crisis has been reportedCitation[[11]]. Some hormonal studies used standardACTH stimulation test have shown subclinical adrenal insufficiency in somepatients with amyloidosis Citation[[5]], Citation[11-12].
The standard ACTH (250 μg) test is a well established initial screeningmethod for assessment of HPA axis. It directly measures not only adrenal cortisolreserve but also provides an indirect assessment of HPA axis. But, 250 μgACTH used in this test is a pharmacological dose which causes a very highlevel of blood ACTH and it is sometimes insensitive. In other words, 250 μgACTH stimulation test provides information only about the ability of the adrenalglands to respond to unusual stimuli and may mask subtle impairment in adrenalfunction Citation[[13]]. It has been suggested that1 μg ACTH may be an adequate dose to provide “physiological”adrenocortical stimulation and it may be more sensitive than the standardACTH test in the diagnosis of more subtle insufficiency of the HPA axis. Onemicrogram ACTH is probably the lowest ACTH dose that will produce a maximalresponse Citation[[14]].
The standard test dose (250 μg) of synthetic ACTH provides a veryhigh blood ACTH concentration. It has thus been a concern that this “supraphysiological”dose may induce false positive cortisol responses in some patients.
In the present study we evaluated the usefulness of low dose ACTH stimulationtest for both assessment of adrenal function and determination of mild adrenalinsufficiency. In our study, 4 of 21 (19%) patients showed reduced cortisolresponse to the low dose ACTH test, and only two of them gave reduced responsesto the standard test (250 μg ACTH). Therefore, we considered that the lowdose ACTH test was more sensitive than the standard test for the determinationof adrenal insufficiency in patients with renal amyloidosis.
In our study we also evaluated 11-DOC and 17-OHP responses to the lowand standard ACTH stimulation tests in the patients with renal amyloidosis.Although 17-OHP responses to both tests were normal, 11-DOC responses werelower than in healthy subjects. Both basal and Synacthen stimulated 11-DOClevels were unexpectedly lower in the patients with amyloidosis. 21-hydroxylaseconverts 17-OHP to 11-DOC and 11 β-hydroxylase converts 11-DOC to cortisol.Low 11-DOC levels resulting from 21-hydroxylase deficiency may cause high17-OHP levels. We could not find high 17-OHP levels in the patients with amyloidosis.Therefore, the cause of low 11-DOC levels in amyloidosis remains to be established.
In the present study the effect of renal insufficiency on cortisol responseto Synacthen stimulation was also evaluted. We found that the cortisol responsesto both Synacthen doses were similar in patients with CRF and with proteinuriaor NS. Therefore we considered that the high adrenal insufficiency rate inour patients was not related with the renal function of the patients.
Although adrenal involvement in amyloidosis has been investigated byhormonal studies, previous studies lack CT imaginations of adrenals. In thepresent study, we have also investigated the adrenal glands radiologicallyusing CT beside hormonal evaluation, and we have seen that adrenal glandsof patients with renal amyloidosis were larger than in healthy subjects. Thisfinding has suggested that there is amyloid deposition in adrenal glands.In our patients, the bodies of adrenals were larger than the limbs of thegland. As known the limbs (tail) of the gland consist predominantly of corticaltissue in the body Citation[[10]]. This finding hasbeen thought that the deposition of amyloid was predominantly in the medullaof the adrenal gland.
In conclusion, adrenal involvement and insufficiency are common in amyloidosis.One microgram ACTH stimulation test is more sensitive than the standard ACTHtest in patients with amyloidosis in the assessment of HPA axis. Low 11-DOClevels in amyloidosis is a new finding and its cause remains to be answered.
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